Plantar fasciitis is a common problem among people who are active in sports, particularly runners. It is an inflammation of the plantar fascia, the thick tendon on the bottom of the foot which is attached to the heel bone (the calcaneus) and fans forwardly to the toes. The plantar fascia maintains the arch of the foot and is placed in tension during walking and running. Any sport where the foot lands repeatedly, such as running or jogging, can overload the plantar fascia and produce an inflammation, usually at the point where the fascia is attached to the heel bone. The reaction of the heel bone to the inflammation is often to produce spike-like projections of new bone called heel spurs. Both the initial inflammation of the fascia and walking on the heel spurs can cause sharp pain.
A broad range of treatments are prescribed for plantar fasciitis, depending upon the severity of the injury and length of time the condition has existed. Among the commonly used treatments are rest, ice, anti-inflammatory/analgesic medication, heel pads, taping, physical therapy and surgery.
Another form of treatment for the condition is the wear of a splint or orthosis which maintains the foot in a slightly dorsiflexed condition, so that when viewed from the side the foot and lower leg form an included angle of approximately 85.degree. or less. Typically, such a splint is prescribed for wear at night while the patient is in bed. This maintains a slight stretch of the fascia when it would otherwise be allowed to shorten while the leg and foot muscles are relaxed during sleep. These so-called "night splints" have in the past taken one of two forms.
The first type of prior-art splint consists of a thick, rigid plastic footbed and a pair of rigid plastic bars extending vertically upward on either side of the footbed. A flexible fabric sheath for encircling the foot and leg is also attached to the foot bed, the sheath being open along its front so that the patient may put on the entire appliance like a boot. The footbed underlies the entirety of the patient's foot, and the bars pass along either side of the ankle and lower leg. Straps are attached to the footbed and the bars and are fastened around the foot and lower leg respectively to secure the splint in position and so maintain the patient's foot in the proper, slightly flexed orientation. Such splints are quite heavy and bulky, and it is common for patients to complain that they are uncomfortable and interfere with sleep.
The second type of prior art splint is a generally L-shaped brace made of a relatively thin layer of molded plastic such as polypropylene. The forward-facing surface of the brace is concave to fit around the rear and sides of the patient's calf, ankle and heel. The bottom portion of the "L" extends forwardly beneath the sole of the foot. These splints generally are lined with padding made from a foam or synthetic pile, and are held in place on the lower leg and foot by means of adjustable straps, typically secured with hook-and-pile fasteners. While such splints are less bulky than the first type of prior art splint, some patients still complain that they are uncomfortable, particularly when worn in bed. The rigid portion of the splint contacts the rear and sides of the heel, ankle and lower leg, and so comes between the patient and the bed mattress during most sleeping postures. The splints may be so uncomfortable that patients cannot get a normal night's rest or may discontinue use of the splint before it has achieved the desired therapeutic result.
Another known type of orthopedic device for the treatment of plantar fasciitis is known as a foot sling. The foot sling consists of a wide band of flexible, padded material which encircles the patient's lower leg just below the knee, and a flexible strap which passes beneath the ball of the patient's foot and is secured at its ends to the upper leg band on either side of the leg. The strap is tightened to pull upwardly on the foot and so maintain it in a flexed position. The foot sling may be uncomfortable to some patient's since the upper leg band must be tight enough around the leg to prevent it from slipping downward when the strap is tightened.